I'm guessing this probably didn't get a lot of attention during the testing of the release candidates, because many (most?) of us have automatic saving on, but I recently wanted to save a best-attempt replay of a level I wasn't able to solve, and that has to be done by saving manually. So, on the post-view screen, I clicked the save replay button.
Expected: Preferably a file dialog, but at least some sort of feedback indicating that the replay was, in fact, saved
Actual: Replay saved silently, with absolutely no feedback. At first I thought my click didn't register until I tried it again and it still appeared to do nothing
I think a file save dialog is the best option here, because if I'm choosing to save a replay manually, there's probably something special about it that would make it desirable to explicitly choose a filename rather than relying on the automatically generated filename.